3S - Using 3 Batteries in Series

3S BMS Protect Three (Groups of) Batteries From Mishap. Combined With Balancing They Are A Perfect Fit For Your Batteries.

A 3S BMS is needed to protect three batteries (or groups of batteries connected in parallel) that are connected in series.

BMS often ship in locked state: no output voltage is available at the output pins.
Locked state is entered whenever over-current protection was triggered.
To unlock the BMS, connect it to a charger. If you did not add a dedicated charger board, apply the appropriate charging voltage to its output terminal.

When connecting batteries to your BMS, make sure you use wires with sufficient diameter for the anticipated high currents.
Also make sure you only use batteries of same type and same state of charge. It is recommended you fully charge all batteries before connecting. All batteries must have the same voltage (voltage difference less than 0.05V). Do not mix batteries from different vendors, types, capacity, or age.

List of 3S BMS

Here is a list of actual 3S BMS breakout boards, separated by maximum current:

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(content created Feb 27, 2024)